Hot air engine



(No Model.)

, V 2 Sheets-Sheet 1. A. P. HURD,

HOT AIR ENGINE.

Patented Sept, 8'. 1885;

(No Model.) 2 Sheets-Sheet 2.

A. P. HURD.

HOT AIR ENGINE.

No. 325,805. Patente d Sept. 8, 1885.

UNTTED STATES PATENT OEEicE.

ALFRED P. noun, on NEW YORK, N. Y.', ASSIGNOR TO THE J. L. MOTT IRON woEKs, or .SAME PLACE.

[HOT-Am ENGINE.

SPECIFICATION forming part of Letters Patent No. 325,805, dated September 8, 1885.

Application filed January 2, 1885.

To aZZ whom it may concern.-

Be it known that I, ALFRED P. HURD, of the city and State of New York, have invented an ImprovementinHot-AirEngines, of which the following is a specification;

Engines have heretofore been made in which the air is confined and subjected to the action of heat to increase its volume and pressure, and thereby cause it to exert more force upon a piston when in a warm condition than it does when cooled. In my improvements I have simplified th construction and renderedizhe engine more efficient than the air-engines heretofore made.

In my engine there are two cylinders with rods and connections to cranks upon flywheels or a shaft, which cranks are at ninety degrees apart. In the heating-cylinder there is a long displ'acer or plunger of sheet metal connected to the displacer-rod. This displacer does not fit closely the cylinder; but there is an air-space around-it. The. gas-burners or fire is at the lower end of this cylinder, and a water-jacket preferably surrounds the upper end of this cylinder. transfer the air frornone end of the cylinder to the other end Whenthe displacer is at the bottom end of this cylinder, the air is dis placed from the heat and cooled by the waterjackct and contracts,and when the displacing plunger rises the air is brought into contact with the heat and expands. From the top of the heating-cylinder there passes a pipe to the bottom of the power-cylinder, in which is an ordinary piston. As the air becomes and the displacer commences to raise and trans fer the air from the cooled portion to the heated 5o portion, and the expansion is again taking place to dri veunthe power-piston as scones-its The displacer acts to (No model.)

crank turns the center, and so on the opera tions are repeated.

In the drawings, Figure 1 is a vertical section of the power and heating cylinders, piston, anddisplacer. Fig. 2 is an elevation of the engine at the power-cylinder side, a portion of the fiy-wheel being removed; and Fig. 3 is a sectional plan the line a: w.

The vertical case A is upon a suitable base,

B, and within the same are grate-harsh for fuel; or there may be gas-buruersor'other sources of heat. Within this case there is the heatingcylinder D, closed at the bottom, and having a movable head, (I, with a gland or bdx, through which thedisplacer-rod e passes; and E is the displacer upon the lower end of the rod e, having guide-lugs at g, to keep the displacer central in the cylinder D.

Above the case'A there are standards G, that support the shaft H, having a crank, h, and connecting rod is to the piston-rod c.

There is a fly-wheel, or, preferably, two flywheels, L, and upon one of these there is a -crank-pin, Z', and a connecting-rod, m, to the piston-rod n, that passes through the head 0 ofthe cylinder P, and is connected to the piston q. There are guide-bars r and a cross- 'head,1", for the piston-rod n, and these guidebars 1' are sustained at their upper ends byarms 8, that'extend out from the;top part of the cylinder D. The head .0 is open or perforated for the atmosphere to passin upon the piston q, and from the bottom of the cylinder P there is a pipe, t, preferably of copper,extending up to the head of the cylinder D, and Opening into such cylinders.

Around the cylinder D there is a waterjacket, R, and the pump T is operated by a connecting'rod to a crank on one of the flywheels L. The watensupply pipe it leads to the pump, the pipe it conveys the waterfrom the pumpinto the jacket R, and the water passes froxnthe jacket B through the air-ves-v sel R to the pipe PE, leading to the reservoir or-plaoe of delivery.

of the heating-cylinder at As the air becomes heated in the cylinder 'D by the fire or flame outside .the'cylindegjt timed so that the piston q is at about halfstroke when the displacer E is at the topof the cylinder D, as indicated in the drawings. The displ-acer E now descends, and by the time the piston 11 reaches the top of the power cylinder P the. displacer E has transferred half the heated'air from the bottom of D to the top. The atmospheric air now begins to -contract by the chilling action of the waterunderstood that the pressure of air Within the engine is about the same as the external piessnre of the atmosphere when the power-piston is at the ends of its stroke, and that the pressure increases to its maximum as the powerpfston rises, and then it decreases again, and that the minimum pressure is when the power-piston is at the middle of its descending stroke.'

I find it preferable to make the displacer of slieet-copper,-with guides g to keep it at the proper distance from the; cylinder D. The sheetcopper is light, andit readily absorbs heat when in the l'owerpart of the cylinder P,

and it gives out the heat to the air to heat up a chamber for elevating water, as these have been used. My present improvements are made for rendering more'eiiicient this class of engines.

- I claim asmy inventionl. The combinatiomwith the vertical powercylinder and piston, of piston and connectingrods, a shaft, fly-wheel, cranks at r .tit angles,

connecting and displacer rods, 2. 'displacer, a

hcatingcylinder in which the displaceris moved up and down, ahead through which the dis'placer-rod passes, and a pipe. connecting the upper end of the heating-cylinder with the lower end of the power-cylinder, substantiall y as set forth.

2. The heating-cylinderclosed-rat itslower end and having a head at the upper end," in coinbinationwith the inclosing-case, pu mp,and the water-jacket, and through which the water is pumpeiha displacer within the heatingcylinder, a rod to the same passing through the cylinder-head, the cranks, shaft, 'fiy-wheel,

power-cylinder,piston, and rods, and the pipe extending from the top of the heating-cylin der' to the bottom of thepower-cylinder, substantially as set forth.

3. The combination, in a hot-air engine, of a vertical power-cylinder and piston, a heatconnecting-rods, cranks, shaft, and fly-wheel,

' and a pipe extending from the bottom of the 'ing-cylin'der, a displacer within the same, the 

